Starting from the firm foundation of the high resolution structure of the MscL channel provided by Rees and coworkers, this proposal weeks to develop new ion channels with novel functions and properties. In addition, this component of the PPG will develop several general capabilities in support of the other projects. The explicit goals are: 1. Establish capabilities for thorough characterization of MscL 2. Develop a new, higher-throughput assay for MscL channel gating 3. Computer modeling of MscL 4. Structure/function studies of MscL 5. Identify open channel blockers 6. Develop MscL derivatives with new gating properties This work will serve a dual purpose. First, we will develop the necessary skills to efficiently characterize MscL and related structures, in anticipation of the large number of new structures that will be prepared in this proposal and in Projects 1 and 3. In addition, we will use MscL as a platform to probe in detail the relationships between molecular structure and channel function. We will also modify the basic MscL channel to incorporate new properties such as ion selectively or gating in response to external stimuli.